Surgical elements such as bone screws are used in various ways, such as in external fixation systems. Currently in order to insert or drive the screws into a bone, tool couplers that vary according to the screw diameter with suitable tensioning devices are used. This is cumbersome to the extent that in any given fixation situation, varying screw diameters are typically used (e.g. knee bridging—in the femur: 6 mm screws; in the tibia: 5 mm screws).
The current couplers must be opened and closed by hand. Despite this, there is often some noticeable play in the screws in the tensioning device. This leads, above all when driven by a power tool, to the undesirable decoupling of the tensioning device and screw even a flinging of the screw into the air.
For example, DE 10 2005 058 868 A1 shows a screwdriver for bone screws that has a gripping part and a shaft that is fastened to it in a torque-proof manner. The free end of the shaft has a non-rounded cross-section and may be inserted in a form-fitting manner into the retainer opening in a head of a bone screw. In order to insert the free end of the shaft in the retainer opening of the bone screw, a grip sleeve must be moved in an axial direction, whereby a helical spring is tensed. This causes a bar to be moved in a longitudinal slit in the shaft in the direction of the gripping part, and retained completely in the grip casing. After the shaft is inserted into the retainer opening, the grip sleeve is once again released by the operator, so that under the effect of the unwinding spring, the bar is moved in the direction of the free end and due to a sliding surface is pushed radially outward against the inner wall of the retainer opening.
DE 199 45 322 A1 describes a chuck for a surgical drilling device. In order to insert a drill wire into the chuck, it is fed through a bore into the end surface of a guide element and on through a passage bore of a jaw guide. The drill wire then hits sliding surfaces of clamping jaws tensed by a leaf spring and thus spreads the clamping jaws outward in a radial direction. The pre-tensed clamping jaws are carried in an axial direction until they hit a supporting element projection with their jaw ends. In a final position, then the clamping surfaces of the jaws are entirely on the drill wire, so that the clamping jaws and the drill wire are clamped together.